1. Field of Invention
The present invention relates to a material used for repair and patching of pavement such as asphalt or cement. More particularly, the present invention pertains to a method and apparatus for applying a tar sand material as a filler and resurfacing substance useful on various pavement surfaces.
2. Prior Art
It is well known that pavement surfaces typically experience various forms of degradation, cracking, separation between sections and other forms of wear which require periodic maintenance. Such pavements include roads, parking lots and virtually any area experiencing traffic and which are subject to weathering conditions which tend to degrade and crack asphalt, cement and other paving materials.
Conventional repair materials for pavement resemble a tarlike substance which must be heated to approximately 400 degrees Fahrenheit and require the crack, opening or other degraded pavement section to be treated with a preliminary coat of base material to improve bonding of the filler, such as an asphalt or tar aggregate. In addition to the heating requirements of maintaining the base sealer and asphalt at high temperatures, application of the material requires an amiable climate in order to obtain satisfactory results.
It is common knowledge that most degradation of pavement surfaces occur during winter where cold temperatures and moisture combine to break up asphalt due to freezing temperatures and the effects of moisture. Such wet pavements and subzero temperatures are generally not suitable for applying asphalt filler. It is not only difficult to establish the proper temperature under such conditions, but it imposes a greater expense. For this reason, road maintenance operations typically occur in the spring after all of the damage has been done. If repair could be effectually accomplished during actual times of more adverse winter conditions, damage would be less serious and less costly. Accordingly, a variety of repair materials have been developed which attempt to provide permanency as well as greater versatility for application during adverse weather conditions. To date, most of these materials have proven to be too expensive to merit broad commerical use.
In some parts of the country, such as Utah, natural tar sand and asphalt deposits enable frequent repair of road damage. For example, in central Utah where large deposits of tar sands exist, roads are constructed utilizing this naturally occurring material. Therefore, when road damage occurs additional tar sand material is used to repair the holes or cracks without special processing or treatment. This naturally occurring material is difficult to work with, however, because it is typically extracted in aggregate chunks which are difficult to reduce to a uniform grain size. Some efforts have been made to soften the material by adding petroleum solvents; however, this appears to adversely affect the quality of the tar sands as a road filler. In its untreated form, tar sands are not effective in filling cracks and are unmanageable for other applications requiring a flowable character. It has not be deemed otherwise practical to liquify the tar sand composition except for processing in a fuel separation process where preservation of the pavement repair properties is immaterial.
Aside from its use as paving material, the primary application of tar sands or bituminous sandstone has been toward production of fossil fuels. Many processes have been developed for separating the bituminous material from mineral content and for treating the bitumen to refine its petroleum products. U.S. Pat. No. 3,556,981 by Cymdalisty and U.S. Pat. No. 4,236,995 by Kruyer are representative of tar sand separation processes. Cymdalisty illustrates one method involving separation of a slurry of bituminous sand and water which is introduced into a body of water so that the bitumen floats to the top and the sand settles to the bottom. Because of their immiscible nature, separation of the petroleum from water is naturally expected. Kruyer illustrates a mechanical system wherein steam and water are mixed with the tar sands in a tumbler and the resulting slurry is subject to separating processes for removing the bituminous components.
U.S. Pat. No. 3,331,765 by Canevari illustrates a separation process for treating athabasca tar sands, which are somewhat different from the Utah type tar sand materials. Many other patents can be cited showing a variety of separation techniques; however, such separation of petroleum from tar sands is not considered relevant to the present invention.
Other patents which discuss preparation of road surfacing compositions include U.S. Pat. No. 3,423,222 by McConnaugha and U.S. Pat. No. 2,068,164 by Cadwell. Each of these disclosures discusses the use of a bituminous material as a bonder for mixing with aggregate. The resulting product resembles asphalt material which is used for treating the road or for filling damaged road surfaces. These disclosures represent the typical process of fabricating a composition by combining bitumen with aggregate material in various combinations. Unfortunately, such compositions have been inadequate as road repair material for reasons which have been previously set forth.